Portable electronic devices, such as cellular telephones, media players (e.g., music, video and/or audio players), and hybrid devices that combine telephone and media playing functionality are known. These devices are sometimes powered by rechargeable batteries such as nickel-cadmium, lithium-ion, nickel-metal hydride, and rechargeable alkaline batteries.
The batteries of such devices are often recharged using standard recharging means and methods. For example, the battery of a device can be recharged by plugging a charger into the device and into a conventional alternating current (AC) outlet. As another example, the battery of a device can be charged by plugging the device into another electronic device using a universal serial bus (USB) connection (such as a USB cable or docking station). However, it may be inconvenient for the user to charge the batteries when, for example, the user is on the road. In addition, a typical recharge will power the battery for only a limited amount of run time (e.g., 10 to 24 hours). After the battery has been drained, the user must recharge or replace the battery to continue using the portable electronic device.
Some portable electronic devices (e.g., calculators) may use solar cells to power the device. Because of the small size of these portable electronic devices, however, the number of solar cells that can be placed on the device is limited. Consequently, while the voltage generated by the solar cells may be enough to power less energy demanding devices, the voltage may be insufficient for portable electronic devices that demand more power.
Furthermore, as an increasing number of advanced features are packed into these portable electronic devices, larger power sources (e.g., larger batteries and more solar cells) are required to power the devices. Thus, there are competing interests between the portability of these devices and the amount of available power.